In the field of modern transaction printers, the objective is to provide simple, compact machines that are easy both to operate and to load. Modern transaction or receipt printers are increasingly called upon to perform a variety of printing functions on a wide range of different paper documents. When a merchant accepts a check for payment for goods or services, it is desirable to verify that the check is drawn on a good account. Magnetic Ink Character Recognition (MICR) readers for reading the bank information encoded on bottom of checks have long existed as stand-alone units. More recently, the MICR readers have been packaged inside the transaction printer so that not only may the MICR characters be read and the account verified, the merchant's check endorsement may be printed on the back of the check in the same operation. The next logical extension of combining functions within transaction printers is to combine a MICR inscribing or encoding station also within the printer. The inscriber prints the amount for which the check has been written using magnetic ink in a predefined amount field area of the check thereby eliminating either a secondary check handling operation at the merchant, a service bureau, or at the bank receiving the merchant's deposit. Banks increasingly are charging commercial depositors a per-check fee for inscribing the amount field. This makes the inscribing operation at the point-of-sale terminal even more desirable. Transaction printers must be compact and the addition of a MICR-encoding station has necessitated skillful design which has required the use of an extremely compact ribbon cassette for holding the special MICR ribbon for the encoder. The present invention provides a cassette containing a direct thermal printing MICR printing tape or ribbon that is both dispensed from and stored upon spools on a common rotative shaft. The new, compact ribbon cassette takes the place of cassettes having spaced-apart, individual, dispensing and storage spools that divide the dispensing and storage functions. Such prior art spools require considerable space within the printer housing.
The invention provides a new style of ribbon cassette for transaction printers that vertically stacks the dispensing spool upon the storage spool. The dispensing and storage spool are supported upon a common shaft that is rotatively supported within the cassette housing.
Uniquely, the compact ribbon casette of the present invention contains an integral friction plate which maintains a predetermined, varying drag on the supply spool of the ribbon to insure quality printing of MICR characters on checks and other similar documents. The new ribbon cassette has a cover plate that contains integrally formed leaf springs designed to bear upon the friction plate disposed over the wound dispensing ribbon. The leaf springs in the cover plate provide biasing against the friction plate, which in turn causes a frictional loading or back drag upon the wound dispensing ribbon spool. The friction exerted upon the dispensing ribbon spool by the friction plate maintains a tension upon the dispensing spool of tape; the tape is thus kept taught as it is dispensed from the spool. This eliminates loosely formed intervals or slack in the tape as it is dispensed.
A uniquely formed chevron, disposed adjacent the dispensing and storage spools, allows for the tape to change elevation and reverse direction from the dispensing spool to the storage spool. The change of elevation allows the dispensing spool and the storage spool to be compatibly disposed for rotation upon the same shaft. In other words, the tape is dispensed from the upper, dispensing spool, changes elevation, and is then wound upon the lower storage spool.
A pair of meshing gears is provided. One gear is rotatively mounted within the housing of the cassette; the other gear is on a pivoting arm 52 biased towards the first gear. The moving, spent ribbon passes between these meshing gears, thus causing the ribbon to be positively advanced without slippage through the cassette.